Introduction: Traffic signals are the controlling devices aimed to reduce crossing conflicts at intersections. However, rear-end and lane-changing conflicts at signalized intersection approaches are a significant problem. This work aims to proactively assess and spatially map the safety and risk at signalized intersection approaches by field data collection and microsimulation modeling using PTV-VISSIMTM. Method: Three signalized intersections operating under mixed traffic conditions were selected and traffic data were collected from the field using video cameras. Post Encroachment Time (PET) was selected as the surrogate safety measure for data analysis. Critical PET values were obtained for each vehicle category by drawing cumulative frequency distribution plots. Microsimulation of the intersections was done using PTV-VISSIMTM and the simulated trajectory data were exported to Surrogate Safety Assessment Model (SSAM). Risk-field models were then developed for different signal change intervals based on the number of critical conflicts. Results: Risk was found to be minimum near the stop-line. From the perspective of a driver approaching signalized intersection, as distance to stop-line reduces, risk increases up to a maximum value and then decreases as the driver gets closer to the stop-line. The location at which maximum risk occurs varies with intersections depending on its geometric and traffic characteristics. High risk area for all intersections was observed to be on middle lane, while considering the entire signal cycle and while considering green time alone. The high-risk area is found to shift toward the median-side lane while considering red time alone. While evaluating safety, it was observed that high-risk area shifts away from the intersection during green signal and shifts toward the intersection during red signal, compared to the risk during the entire signal cycle.

Modular blocks are used for various pavement construction. Modular blocks are categorised based on the materials used for manufacturing such as bitumen, cement, concrete, fly ash, and soil. This study is focused on modular blocks manufactured using bitumen. Bituminous blocks are modular blocks manufactured by using bituminous mixtures. Bituminous blocks are used for road construction in earlier days under the name of historical pavement. Bituminous blocks offer several benefits during the construction and maintenance stages of road works. The main aim of this study is to develop a comparative analysis based on the performance of bituminous blocks in the laboratory and the finite element model using Abaqus. This study is limited to the performance analy sis of bituminous blocks for the rutting criteria using wheel rut testing. Bituminous blocks have revealed that the rutting values are within the prescribed limit based on laboratory and finite element model results. The percentage variation of rut depth based on the finite element model result and laboratory result is significantly less.

Most road surfaces globally are constructed using bituminous materials. The construction of new roads and the maintenance of existing ones demand a huge amount of virgin natural aggregates. Depletion of resources that takes place during the construction of the road has an impact on cost and also on the environment. Hence, there is a need to reduce virgin aggregate use for bituminous pavement construction. This can be achieved by utilizing sustainable materials such as marble waste and reclaimed asphalt pavement (RAP) in hot mix asphalt (HMA)-type road construction. This research work is focused on sustainable development goal (SDG) 12, exclusively on the target number 12.5 which describes the recycling and reuse of materials. However, no investigations were seen to be reported on the integrated utilization of sustainable materials and RAP in bituminous paver blocks. The bituminous mixes were evaluated based on strength and compared with the control mix in this study. Bituminous paver blocks were then cast using sustainable materials and tested in the laboratory to assess the performance of the blocks through a compression test, Cantabro loss test, and wheel rut test. The test results gave satisfactory values; hence, these bituminous blocks can be used for service maintenance of the pavement structures. The study indicates that using sustainable material along with RAP in blocks can provide an eco-friendly, easily maintainable pavement system which makes it a key approach to SDG 9 as well, in terms of innovative infrastructure solutions.

The climatic changes we are currently experiencing are so drastic that the existing pavements are not able to keep up with them; among these, the floods are more severe as they occur more frequently than other hazards. Aerogel is a substance that is highly resistant to water. This paper presents the study of application of aerogel in bituminous pavement construction. Since silica-gel is having similar features, for comparison silica-gel modified pavement is created, which is used to compare the results obtained with the aerogel-incorporated bitumen pavement. The FEM analysis results of both silica-gel and aerogel-modified bitumen are compared with the standard bitumen pavement analysis results. Similarly, aerogel-incorporated concrete pavement model is created, and results are compared with the standard concrete pavement. The aerogel-incorporated pavement performs well compared to silica gel while maintaining the required strength required for the standard pavement.

Intersections pose special safety concerns because of the high probability of critical conflicts resulting from unsafe driver actions and maneuvers. The absence of movement priorities, lack of lane discipline, forced entry by non-priority movements, etc., at unsignalized intersections violate the assumptions involved in capacity calculation. A key aspect of this study is to analyze conflicting flows at unsignalized intersections, which vary depending on site conditions and geometrical features in heterogeneous traffic environments and to estimate movement capacity at unsignalized intersections. At unsignalized intersections, vehicles from different directions cross and turn simultaneously, resulting in severe vehicle-vehicle conflicts. Thus, traffic safety is an important aspect to be evaluated at unsignalized intersections. The study also aims at conducting a safety assessment at unsignalized intersections using the microsimulation model (VISSIM) coupled with the Surrogate Safety Assessment Model (SSAM). The study found that SSAM is adaptable to intersections of varying geometry and serving heterogeneous traffic.

An autonomous vehicle (AV) or driverless car ensures safety using advanced sensor and positioning technologies with little or no human input. With numerous emerging technologies, it is important to know the potential capacity effects of AVs to aid our decision-making process with future investments. As AVs are not widely used especially in developing countries like India, it is difficult to study the behaviour of AVs and their interactions with other vehicles in the field. Hence, the mid-block section of a two-lane highway incorporating AVs is simulated using VISSM in this study to analyse how AVs impact the capacity of the highway. Passenger cars are replaced by autonomous cars in the model and the model is calibrated using travel time as measure, and the change in the capacity for various penetration rates of AV is estimated. The study gave promising outputs in terms of capacity enhancement and found that the introduction of the AVs can enable better utilization of the available road space.

Bituminous blocks are utilized for road construction all over the world in the name of historical pavement. Bituminous block pavement has a number of advantages in terms of faster construction and maintenance of road projects. The performance of any pavement structure is generally influenced by the thickness of the layer provided, which is determined by the structural and physical properties of the materials available for construction. Only a few experimental experiments on bituminous block pavement have been conducted. No studies were reported on the effective thickness of bituminous block pavement using the finite element technique. The multiple constraints associated with conducting experimental work on bituminous blocks of different thicknesses can be reduced by employing a finite element technique. Bituminous block pavement was tested in this study by altering the thickness, which was fixed according to the code specification. The bituminous block pavement thicknesses employed in this investigation were 50 mm, 55 mm, 60 mm, and 65 mm. ABAQUS software was used to perform a finite element study of the bituminous block pavement. The analysis showed that as pavement thickness increases, the deformation values decrease. The minimum and maximum deformation obtained is about 8–24

Pedestrians are the most vulnerable road users and they are highly susceptible to conflicts at mid-block cross-walk locations. They are prone to a high risk of injury from vehicular impact incidents and their decision making behaviour at unmarked cross-walks (UCWs) is more critical than at marked cross-walks (MCWs). The objective of this study was to determine level of safety thresholds and warrants for both marked and unmarked pedestrian crossing facilities at urban mid-block sections under mixed traffic conditions. Data were collected at MCWs and UCWs in four different locations in Trivandrum city, India. The crossing behaviours of pedestrians at both types of cross-walks were compared by analysing characteristics such as gap acceptance, a surrogate safety measure (post-encroachment time (PET)), waiting time, crossing time, platoon size, type of critical vehicle and critical gap. The multiple linear regression technique was used to develop gap acceptance models for MCWs and UCWs. The pedestrian level of safety (PLS) criterion is proposed; the PLS describes the safety of pedestrians at cross-walks and warrants for crossings based on PETs. The developed PLS thresholds and the pedestrian–vehicle interaction values were correlated to the PETs to develop the pedestrian crossing warrants.

Self-healing materials are those that have a potential to repair mechanical damages and cracks, without the need for human interference and restore their original set of properties. Incorporating self healing property of bitumen into road design process helps to extend the life of asphalt pavements. Traffic load repetition and ageing causes microcracks in the pavement which gradually leads to pavement failure. This necessitates frequent pavement maintenance procedures. Self healing property of bitumen can automatically repair damage and recover strength. By reducing premature ageing of asphalt pavements, self healing asphalt can reduce amount of natural resources used in road maintenance and reduce environmental pollution by decreasing CO2 emission in maintenance process. Addition of rejuvenator to asphalt material is the widely used method for achieving self healing of bitumen. A comprehensive understanding of the self healing properties of bitumen such as its ability to heal, factors affecting healing property can considerably help in the development of durable and sustainable asphalt pavements. ABAQUS is 3D finite element analysis software used for predicting mechanical behavior and pavement performance subjected to various traffic factors. In this study, modeling of bituminous material modified with rejuvenator is done using ABAQUS software in which model dimensions, element types and meshing strategies are taken by successive trial and error to achieve desired accuracy and convergence of the study. Analysis of self healing asphalt modified with microcapsule containing rejuvenator shows that there is a reduction of stress around the microcapsule region.

The necessity to extend road service life and improve performance has increased the usage of pavement reinforcements in recent times. Geogrids are progressively being employed as a reinforcement in a wide range of engineering disciplines. The flexible pavement is among the core area, where enhancement in performance of pavement service life is needed. The purpose of this modelling is to study how geogrids in pavement work using the finite element method using ABAQUS software. This research evaluates the effectiveness of geogrid-reinforced pavement in terms to reduction in rutting under load. The finite element system was used to do analysis on models of unreinforced and reinforced roads. The findings of the finite element study demonstrate that adding geogrids between the pavement layers lowered surface distortion. The findings attained show that the grids are frequently widely utilized enhance the effectiveness of flexible pavements and may contribute significantly to crack resistance and the prevention of permanent deformation.

The traffic flow at intersections is generally chaotic, and signalization is a control measure to reduce this chaos. Heterogeneous traffic at signalized intersections behave much differently from homogeneous traffic. Also, in many countries, nonlane-based traffic prevails; hence, designing control systems for such situations is a challenging task. Traffic simulation helps the analyst to model the behavior of such complex systems. Cellular automata (CA), a recent entrant in traffic flow modeling, represents the traffic flow by means of simple rules, and thus has proved to be a versatile tool in traffic simulation. The present study aims to develop a computationally efficient traffic flow simulation model integrating the concepts of cellular automata and driver-vehicle-objects, thus making a behavioral model of traffic. The model emphasizes the diversity in human behavior, and represents the traffic using the minimal modeling concept of CA. To represent multiple vehicle types, a multicell representation was adopted. Further, to address the issue of nonlane-based movement, new lateral movement rules were proposed. The model incorporated behavior at amber and lateral movements, thus attempting to achieve a near to reality representation of nonlane-based heterogeneous traffic. The model was calibrated and validated using delay data from selected intersections in India. This model was then used to predict saturation flows at signalized intersections. The model performed reasonably well in predicting the delays, but the saturation flow values showed up to 30% variability. DOI: 10.1061/(ASCE)CP.1943-5487.0000207. (C) 2013 American Society of Civil Engineers.

Signalisation is a traffic control strategy to ease the competition by providing right-of-way in a cyclic manner to conflicting traffic at intersections. Saturation flow is a major component in the design of signals, and is influenced by a variety of factors like vehicle composition, intersection geometry and driver's behaviour. The highway capacity manual (HCM) has recommended a saturation flow model primarily for homogeneous conditions, with limited ability to address heterogeneity. But the traffic in many parts of the world is highly heterogeneous and hence, defining a unified saturation flow concept is a challenging task. The variability in vehicle types necessitates the use of passenger car units (PCUs). This article proposes a methodology to develop a saturation flow model based on dynamic PCUs by a microscopic analysis. Field data from intersections of three Indian cities - Jaipur, Bangalore and Trivandrum - is used for the study. PCU values are derived from the field data, by minimising the difference between the observed and the ideal flow profiles. A new saturation flow model is then developed using the regression method. The model is validated with the saturation flows collected from different locations. In addition, the flow predicted by the saturation flow model is used to estimate delay using the HCM and Webster's models, and these delays are compared to the observed delays. The proposed model resulted in lower error compared to the conventional flow estimation techniques.

A significant part of the world, especially in most of the Asian countries, has heterogeneous traffic characterized by diverse vehicles, changing composition, lack of lane discipline, etc., resulting in a very complex behavior. Microsimulation is, therefore, highly suited to model such traffic. However, these models need to be calibrated before their application. Although several studies have been reported in the literature on the methodologies for calibration, all of them have focused on homogeneous traffic conditions having good lane discipline. In highly heterogeneous traffic, several other factors such as traffic composition and static and dynamic characteristics of vehicles have to be considered in the calibration process. Moreover, side-by-side stacking of vehicles across the road width occurring in the absence of lane discipline should also be modeled. Hence, a methodology for representing nonlane-based driving behavior and calibrating a microsimulation model for highly heterogeneous traffic at signalized intersection is proposed. Calibration parameters were identified using sensitivity analysis, and the optimum values for these parameters were obtained by minimizing the error between the simulated and field delay using genetic algorithm. The proposed methodology is illustrated using Verkehr in Staedten simulation, a widely used psychophysical car-following model based microsimulation software. Signalized intersections having diverse traffic and geometric characteristics from two cities of India are taken as a case study.